CHM1020 Exam 3 Study
How do temperature and activation energy relate to affect a reaction?
- Increasing temperature provides particles with more kinetic energy, so the activation energy is more easily overcome
which of the following are potential products of the combustion of coal and other hydrocarbons, in addition to CO2 and H2O?
- SO2 - NO2
Which of these statements correctly express the second law of thermodynamics? Select all that apply
- The entropy of the universe is constantly increasing - Energy conversions cannot be 100% efficient
Which of the following power plants has the highest net efficiency?
- a plant that produces 450 kJ of electricity from 600 kJ of heat (this plant is 75% efficient compared to 25, 45, and 60% of the other plants)
Refinery gases _____
- are found in the "lightest" fraction of crude oil - may be used as fuel at the refinery - include methane
which of the following options correctly explain why an energy change calculated using bond energies may not match experimental results?
- bond energies vary between molecules, even for the same pair of elements - bond energies are given for molecules in the gaseous state
which of the following are desirable qualities for a fuel?
- by-products formed from combustion of the fuel should not harm the environment - the fuel should be easily transportable - it should ignite at a fairly low temp
match each type of reaction correctly to its representative example
- catalytic cracking- C18H38 -> C9H20 +C9H18 (bigger into smaller) - catalytic combination- 2C4H8 -> C8H16 (smaller into bigger) - catalytic reforming- C8H18 (n-octane) -> C8H18 (iso-octane) (rearranging atoms to form different isomers)
Which of the following products are separated from crude oil? Select all that apply
- industrial oils and lubricants - jet fuel - starting materials for plastics and other carbon-based products
Which of these statements correctly describes the process of distillation?
- it is commonly used to separate the components of crude oil - it involves heating a mixture t boiling and recollecting the vapors
match each grade of coal to its description
- lignite- most similar to wood or peat, releases relatively little energy - bituminous- contains relatively high percentage of carbon - anthracite- contains high amounts of carbon and low sulfur, making it the most desirable grade of coal
which of the following options correctly describe activation energy?
- lower activation energy generally results in faster reactions - increasing the temperature allows more particles to have sufficient energy to overcome the activation energy barrier
which of these properties make one grade of coal more desirable than another?
- lower oxygen count - higher C content - lower sulfur content
which of the following are examples of fossil fuels?
- natural gas - petroleum - coal
which of these statements correctly describe coal mining?
- near surface foal can be mined more safely than other deposits - mining debris can damage or bury nearby water systems
In addition to providing fuel, crude oil also supplies components used as feedstocks to produce _____
- plastics - pharmaceuticals - fabrics
A liquid will have a higher boiling point if its intermolecular attractions are _____
- stronger
which process describe steps in the production of fossil fuels?
- sunlight energy is captured by plants during photosynthesis - increasing temperature and pressure cause new chemical reactions that convert plant matter into fossil fuels - plants partially decompose, releasing stored energy and producing H2O and CO2
The boiling point of a liquid is the temperature at which _____
- the vapor pressure of the liquid equals the external pressure
Which of the following options correctly describe internal combustion engines? Select all that apply
- they are less efficient than most power plants - more than half the energy they produce is lost as heat - they use the has products of combustion to drive mechanical pistons
which of the following options correctly describe fossil fuels?
- they are not sustainable at the current rate of use - their use raises atmospheric CO2 levels
what are the greatest advantages in biofuel?
- they can release less CO2 than fossil fuels - they are renewable
The diagram below shows a simplified version of a fractionating column used in the petroleum industry. The position marked ________ corresponds to the cracker where large molecules are broken into smaller molecules.
-- a) C a) C (Remember that the cracker will split compounds found lower in the column into two other portions.) b) D c) A d) B
The diagram below shows a simplified version of a fractionating column used in the petroleum industry. The compounds that are obtained at position D are
-- a) asphalt a) asphalt. (Remember that items with the highest boiling points will be at the bottom of the column.) b) jet fuel. c) gasoline. d) refinery gases.
The burning characteristics of a gasoline can be improved by converting the octane it contains into isooctane. This conversion requires the use of expensive catalysts such as
-- a) platinum and palladium a) platinum and palladium. (Remember that group 8B elements are the best catalysts.) b) biological enzymes. c) gold and titanium. d) ultraviolet radiation.
According to the graph below, the net U.S. import of petroleum drastically decreased during the years
-- b) 1977 to 1982 a) 1985 to 1990. b) 1977 to 1982. (Notice the decrease of nearly 50 percent.) c) 1973 to 1975. d) 1970 to 1977.
The heat of combustion for the combustion of propane, C3H8 + 5O2 ⟹ 3CO2 + 4H2O , is equal to -2,200 kJ. This is an example of a(n) _________ reaction.
-- b) Exothermic a) not enough information b) exothermic c) endothermic d) precipitation
Oxygenated gasolines are blends of petroleum-derived compounds with oxygen-containing compounds. Which of the following oxygenated compounds has been discontinued in some states because of potential health risks?
-- b) MTBE a) Ethanol b) MTBE (Remember that MTBE is soluble in water and can contaminate wells.) c) Methane d) Methanol
As alakanes (hydrocarbons) become larger/longer (more carbons) the boiling point ___________.
-- b) increases a) stays the same b) increases c) decreases d) no one knows
Which law of thermodynamics states that the entropy, or randomness, of the universe is increasing?
-- b) second a) zeroth b) second c) third d) first
Given the following reaction what is the energy of this reaction: N2 + O2 ⟹ 2NO ? Use the following bond energies N≡N = 946 kJ/mol, O=O = 498 kJ/mol, N=O = 607 kJ/mol
-- c) -230 kJ a) +837 kJ b) -607 kJ c) +230 kJ d) -230 kJ
Which of the following is a proper use for a calorimeter?
-- c) Measuring heat of combustion a) Measuring temperature of a mixture b) Measuring entropy of a reaction c) Measuring heat of combustion (Remember that these work to find temperature change that occurs due to a chemical reaction.) d) Measuring the amount of oxygen consumed in a combustion reaction
Advertising claims sometimes state that adding something mechanical to a car's engine will allow it to recover 100 percent of the energy that comes from burning gasoline. You should be skeptical of such claims because they violate the
-- c) second law of thermodynamics. a) law of conservation of matter. b) first law of thermodynamics. c) second law of thermodynamics. (Remember that no process may even be 100 percent efficient due to entropy.) d) activation energy requirements of all chemical reactions.
In the petroleum industry, what does a refinery do?
-- d) It separates crude oil into fractions consisting of compounds with similar boiling points a) It mixes natural gas or coal with crude oil in order to remove the impurities from the crude oil b) It produces the machinery by which crude oil is removed from the ground c) It separates crude oil from the coal with which it is almost always found d) It separates crude oil into fractions consisting of compounds with similar boiling points
A(n) _________ is a molecule with the same formula but different chemical structure.
-- d) isomer a) isotope b) solution c) catalyst d) isomer
In an exothermic chemical reaction
--a) heat is released as the reaction proceeds a) heat is released as the reaction proceeds. (Remember the exo- means "out of.") b) the mass of the products is less than the mass of the reactants. c) heat is absorbed as the reaction proceeds. d) the mass of the products is greater than the mass of the reactants.
The following molecules contain only single bonds.NH3(g) + 3F2(g) → NF3(g) + 3 HF(g)The bond energies are: N — H 391 kJ/mol; F — F 158 kJ/mol; N — F 272 kJ/mol; H — F 566 kJ/mol. Which is the heat evolved or absorbed per mole of NH3 that reacts with F2?
--b) a) +289 kJ/mol b) -867 kJ/mo (Take the sum of all bonds formed minus all bonds broken.) c) +867 kJ/mol d) -289kJ/mol
Carbon is in Group 14 (IVA) and has_____ valance electrons. In order to attain a full octet in its outer shell it will therefore form ____covalent bonds.
--c) 4;4 a) 4;2 b) 6;4 c) 4;4 d) 2;2
Assume that coal can be represented by the chemical formula C135H96O9NS. If 6.0 tons of coal is burned, what mass of nitrogen is found in the NO produced by this process?
.0441 tons nitrogen molecular mass of coal= 1906.1 g mass of nitrogen in coal: % weight N= mass N/molecular mass coal = 14.01/1906.1 x100 = .735 6.0 tons x .735/100= .0441 tons nitrogen
place the steps for the production of ethanol from corn in order, with the first step at the top
1- corn kernels are mixed w water 2- enzymes break down starches into glucose 3- yeast fermentation converts sugar into ethanol 4- the mixture is distilled
they following are the steps seen when a Newton's cradle is used. Place them in the correct order
1- one ball is lifted by hand, giving it potential energy 2- the ball is released, converting potential to kinetic as it falls 3- the falling ball strikes the unmoving balls, and kinetic energy is transferred through them to the ball on the opposite end 4- the opposite ball swings upward, converting its kinetic energy to potential energy
place the following objects in order to decreasing kinetic energy
1- semi truck moving at 45mph 2- car moving at 45mph 3- car moving at 10mph 4- bike moving at 10 mph
the heat of combustion for n-heptane is 4817 kJ/mol. How much heat is released if 250 g of this liquid burns completely?
1.2x10^7 kJ
If an office building requires 8.7x10^10 kJ of energy per day, how much energy must be generated at a 42% efficient power plant to supply the building?
2.1x10^11 kJ
according to the label on a soft drink, one serving provides 115 kcal. If all of this energy is used to lift 1.0 kg blocks, how many blocks can be lifted 2.0 meters?
2.4x10^4 blocks
a coal burning power plant generates 9.5x10^6 J per year. If the coal yields 33 kJ/g, how many grams of coal was burned each year?
2.9x10^12 g convert J to kJ: 9.5x10^16 x 1 kJ/1000 J= 9.5x10^13 kJ how many g of coal are burned?: 9.5x10^16 x 1 kJ/1000 J x 1 g/33 kJ= 2.9x10^12 g
based on the energy diagram given, what happens when hydrogen reacts with oxygen to form water vapor?
483.6 kJ of heat are released for every mole of O2 that reacts
if a person consumes 5.7x10^5 kcal in a day and 1 barrel of oil can produce 3.7x10^6 kcal, what is the equivalent of energy consumed per year by that person in terms of barrels of oil?
56.22 barrels kcal per day/kcal per year = # # x365= answer 5.7x10^5/3.7x10^6= .154 .154 x365= 56.22
in this figure, the energy difference (in kj) for each fuel is its energy content. Calculate the energy content of methane in kJ/mol. Express as positive number
8.02x10^2 kJ/mol to convert kJ to mol, multiply by molar mass: 50.1 kJ/1 g x 16.0 g/1 mol= 8.02x10^2 kJ/mol
a coal burning power plant generates electrical power at rate of 850 megawatts (MW) or 8.5x10^8 J/s. The plant has an overall efficiency of 31% for conversion heat to electricity. Given this efficiency, how much heat is produced in 1 year of operation?
8.6x10^16 J 31%= 8.5x10^8/heat x 100 J to J/yr: 8.5x10^8 x 3600 x 24 x 365= 2.68x10^16 J/yr Find heat: 2.68x10^16/.31 = 8.6x10^16 J
Temperature
A measure of the average kinetic energy of the atoms/molecules in a substance.
Heat
Flow of energy between objects with different molecular kinetic energy
Potential or Kinetic Energy?
Potential: - battery - food - ball at top of hill Kinetic: - ball rolling down hill - person running - spinning motor - wave in the ocean
what effects does a catalyst have on a chemical reaction?
a catalyst lowers the activation energy for a reaction
endothermic
a reaction that absorbs heat
exothermic
a reaction that releases heat
the n in the name n-hexane indicates that
all the carbon atoms are joined in a straight chain
what was the result of the energy balance study on the production and use cycle of biodiesel?
biodiesel generates over 300% more energy than is required to produce it
match each process correctly with the associated energy change
bond breaking- absorbs energy bond forming- releases energy
match each type of hydrocarbon combustion with the products formed
complete combustion- CO2 and H2O incomplete combustion- CO2, H2O and CO
a structural formula in which carbon-to-hydrogen bonds are not shown explicitly is called a ___ structural formula
condensed
The intermolecular attractions between nonpolar molecules such as hydrocarbons are called London ____ forces
dispersion
the process of water evaporating from your skin is _____ because heat is _____
endothermic; absorbed
exothermic or endothermic
exo: - mammal metabolizing food - reaction in a hot pack - burning candle - setting off firework endo: - water evaporating - reaction in cold pack - ice melting - photosynthesis
any substance that can be burned to produce heat or work is called a _____
fuel
molecular formula
gives the ratio of elements in the compound
the common name of the byproduct of biodiesel synthesis is called
glycerol
the "_____ zone" is the intersection of healthy ecosystems, healthy economies, and healthy communities
green
a calorimeter is used to measure the _____ released or absorbed by a reaction
heat
Compounds containing only carbon and hydrogen are called
hydrocarbons
clean coal technologies are best described as methods of
increasing the efficiency and decreasing the harmful emissions of coal power plants
Attractions between individual molecules are called _____ attractions.
intermolecular
which of the following options best describes isomers?
isomers contain the same number and type of atoms, but they are connected in different ways
how can sustainable energy production be achieved using combustible fuel sources?
it cannot. combustion must be supplemented by additional renewable energy sources
rank hydrocarbons in order from lowest to highest boiling point
methane < propane < pentane < octane
naming alkanes
methane- CH4 ethane- C2H6 n-pentane- C5H12 n-heptane- C7H16
structural formula
shows the placements of all atoms in the compound
energy conversion can never be 100% efficient beacuse
some amount pf potential energy is always dissipated as heat
A sample of fuel is burned in oxygen, producing heat and light. Based on the first law of thermodynamics, which statement must be true?
the energy lost from the fuel and oxygen is equal to the energy of the heat and light
the energy contained within fossil fuels originates from the conversion of _____ to _____
the energy of sunlight; stored chemical potential energy
the net efficiency of the erengy transformation in a power plant is beast described as
the ratio of electrical energy produced to the energy supplied by the fuel
to convert a fat or an oil into a biodiesel, the compound is generally heated with an alcohol and a catalytic amount of NaOH. What change results from this process?
the triglyceride is broken into smaller pieces that evaporate more readily
success in business today is judged on three criteria, including profitability, fair treatment of employees, and environmental impact. This is known as the _____ bottom line
triple
energy is the ability to do _____ or to produce _____
work, change
